Sorry that I'm so late to this game. I bought a pair of O-netics DAC output transformers from Budp about a year ago and finally got them installed in my Behringer DEQ2496. I used 560ohm series resistors in each leg of the primary with no secondary loading. The bass seemed very rolled off until I jumpered out the series resistors. Now I measure flat output through the bass range compared to 1kHz.

The dynamics are very good and small inner details are much more resolved. But, it seems like the sound gets harsh as I increase the volume. I'm playing at volumes that I've always used but never with this harshness before. I have a low powered PP tube amp. Do you think I'm getting the amp into clipping or near it's limits with the increased dynamics? I have to decrease the volume quite a bit now before this problem subsides. The only thing I've tried so far is adding a 2.2k resistor across the primary since I've seen it mentioned that sometimes a shunt resistor will even out the impedance at higher frequencies.

It's good to control THD at the output of your amp at the different volume settings, or, at least check the signal form. There might be the case that you got a bit more amplitude with the transformers (if they work like 1:2 or so), and therefore may overload input bias at the tubes drivers.

Thanks. I recently corresponded with Budp of O-netcs from whom I bought the output transformers. He gave me some good advice regarding the use of primary side series resistance to control the loading on the DAC. I am making progress. He suggested that in the end the optimal value of resistors for sound quality would be something under half of the recommended resistance. Am doing trials now.

Hi, I'm currently using Tamradio transformers (same as post 203) direct off DAC chip no loading resistors or caps...
Is this optimum? Some people say use nothing and other posts use loading resistors and caps.
Would someone kindly tell me what I should be using with these Tamradio Output transformers? I think they are 600ohm 1:1.

I can swore by all gods an devils that using of resistor will decries SQ to half.
I had 15 Ohm as "isolation" (witch people crying) for a along time and never satisfied with clarity of sound. just for curiosity soldered the output caps before the resistors. Haven means something now ...

Thanks. I recently corresponded with Budp of O-netcs from whom I bought the output transformers. He gave me some good advice regarding the use of primary side series resistance to control the loading on the DAC. I am making progress. He suggested that in the end the optimal value of resistors for sound quality would be something under half of the recommended resistance. Am doing trials now.